Electrical protective system



Fil ed March 14, 1935 z Sheets$heec l INVENTOR i '2 ,3 B! V ATTORNEYarch 3, 19%. L. K. SWART fi p ELECTRICAL PROTECTIVE SYSTEM Filed March14, 1935 2 Sheets-Sheet 2 Ejecondar of EMF/I751- 5225513332 R circuit.m-iq 7b Winding; 49 lelay R10 49320- ll; B Battery.

Slow operzztlflg re ay INVENTOR ZESW i ATTORNEY Patented Mar. 3, 1936ETED STATES PATENT OFFICE ELECTRICAL PROTECTIVE SYSTEM Applicaticn March14, 1935, Serial No. 11,177

7 Claims.

This invention relates to electrical protective systems or moreparticularly to arrangements for simultaneously grounding a plurality ofconductors when induced voltages above a fixed and 51 predeterminedvalue become impressed thereon. The arrangements of this invention alsoare adaptable for the purpose of testing the apparatus and in thetesting operations potentials may be applied either to the variousconductors and ground or to the conductors alone.

Pairs of protector blocks each having an air gap which breaks down at apredetermined potential are used in the telephone art to protect each ofa number of telephone conductors from 15 high voltages set up therein byone or more sources extraneous to the circuits themselves. In thesearrangements a resistor, saturating reactor or transformer is interposedin the ground connection of each pair of protector blocks or in :0 thecommon ground connection of all protector blocks. In some arrangementsthe current derived from the impedance drop across the resistor, reactoror transformer, is rectified by a copper-oxide type of rectifier. Thisrectified our- 35 rent is applied to a relay which when operated shuntsa pair of protector blocks or, if desired, the rectified current may becaused to operate a relay which will apply local battery to a group ofshort circuiting relays, employed for short cir- 30 cuiting all theprotector blocks during the period in which the extraneous voltageexists. In another type of relay protector arrangement the currenttraversing one or all of the protector blocks may be applied to asaturating reactor or transformer which operates an alternating currentrelay the contacts of which apply local battery to a multiplicity ofshort circuiting relays. The contacts of these relays short circuit allof the protector blocks, thus preventing permanent grounding of theseblocks.

At present the commonly employed low voltage carbon protector blockshave a considerable variation in operating range depending upon thehistory of previous operation of the blocks, the impedance of the line,the humidity, etc. In order to provide operation of protective equipmentat a predetermined fixed value of voltage, the carbon protector blockalone can not be depended upon to give operation within a narrow marginof operating voltage. If a gas discharge device, however, is shuntedaround the protector block in series with a relay, condenser, etc, aswill be described hereinafter, a fixed operating voltage, depending onthe design of the tube may be obtained. This operating voltage can bemade to lie slightly above the normal telegraph and ringing voltagesapplied to the line conductors and considerably below the 250-voltminimum of a carbon protector block. Furthermore, by the use of gasdischarge devices it becomes practicable to operate the device fromvoltage applied to a line wire from a remote point. A particularprotective device situated along an open-wire line can be selected foroperation by knowing the conductors on which the various gas dischargedevices are applied. Furthermore, remote testing may be carried out byapplying voltages between wires equivalent to the voltage required tooperate the device from a single conductor to ground. When testing byapplication of voltage between the conductors, the voltage to groundwill be one-half of that required to operate the device from a singleconductor to ground, as will be shown hereinafter. Thus, there will be avery wide margin in the operating voltage of the device. This is ofdecided advantage due to the very wide operating values to be expectedof carbon protector blocks some of which as before stated, might operateat a very low voltage and ground in the process of testing. This resultsin lost service time and necessitates sending an attendant out to someremote point to replace the blocks before the circuits can be restoredto normal.

At times it may be desirable to provide for remote testing and yet notemploy the gas discharge devices to operate from voltages to ground butfrom voltages between line Wires only. This is readily accomplished bythe apparatus of this invention, as will be shown thereinafter.

This invention will be better understood from the detailed descriptionhereinafter following when read in connection with the accompanyingdrawings in which Figure 1 illustrates a plurality of adjacentconductors two of which are respectively connected to networks ofgas-filled tubes and relays; Fig. 2 illustrates a modification in whichthe two relays of Fig. 1 are replaced by a single relay; Fig. 3illustrates a biasing arrangement of batteries connected between two ofthe conductors, the arrangement also including two oppositely directedgas-filled tubes; Fig. shows the two conductors connected by a singletube and a single biasing battery; Fig. 5 illustrates a modificationwhich includes a trigger tube of the threeelectrode type; and Fig. 6shows another modification which includes two tubes and one of thewindings of an associated relay connected in series with each otherbetween the two parallel conductors.

In Figure 1 reference characters W1 to W4, inclusive, represent four ofa plurality of conductors or circuits which may be supported by a commonprotector pole. Each of these conductors may be connected to groundthrough an individual protector block and a common reactor or saturatingtransformer T, as shown. The various protector blocks are designated P1to P4, inclusive. The lower terminal of each of these blocks isconnected to the upper terminal of the primary winding L1 of thetransformer T. Each upper terminal of these protector blocks isconnected to conducthe relays R10 and R20.

tors W1 to W4, as shown. Each of the various protector blocks mayinclude two carbon electrodes spaced from each other by a gap ofpredetermined width.

The transformer T includes also a secondary winding L2 which isconnected to the respective upper windings of relays R1 and R2. Each ofthese connections may or may not include a series condenser. Thecondenser if desired can be used to tune the circuit of the upperwinding of the relays R1 and R2 to some definite frequency such as thatof some nearby source of extraneous induced potential.

The relays designated R10 and R20, associated with the protector blocksP1 to P4, inclusive, are arranged so that their windings are connectedin parallel, the parallel circuit being in series with a battery B andthe armatures and contacts of the relays R1 and R2. When either or bothof the relays R1 and R2 become operated, current will flow from thebattery B over the armatures and contacts of these relays and throughthe windings of The armatures of these latter relays will becomesimultaneously attracted to their contacts and will simultaneously shuntall the protector blocks. They will also shunt the gas tube devicesconnected thereto and extinguish the tubes, as will be shownhereinafter, and at the same time shunt the arc across all of theprotector blocks P1 to P4.

In addition to the above described relay equipment a pair of conductors,such as W1 and W2, which traverse the entire exposure are chosen aspilot conductors to which are applied at a given protector pointcondensers, gas discharge tubes, resistances, etc., which will now bedescribed. A condenser C1 is connected to conductor W1 and to the anodeof rectifying gas tube N411 and to the cathode of rectifying gas tubeN421. The cathode of the gas tube N411 is connected to the cathode ofthe rectifying gas tube N441 and to lower terminal of winding l of therelay R1. The upper terminal of the winding I of relays R1 and R2 andthe lower terminal of Winding 2 of these relays are connected to eachother as shown. The upper terminal of winding 2 of relay R1 is connectedto the anodes of rectifying gas tubes N421 and N421. The anode of gastube N441 is connected to the cathode of gas tube N431 and to ground.Gas tubes N411, N421, N431 and N441 are shunted respectively byresistances Z and these are of equal value if these gas tubes have equalbreakdown potentials. The values of each shunt resistance Z should be ofthe order of from 500,000 to 1,000,000 ohms or higher depending on theleakage between the elements of the gas tubes. The conductor W2 isconnected to a similar arrangement except that the relay R2 isassociated with this second arrangement. Windings 3 of both relays R1and R2 are connected to the secondary winding L2 of the transformer'T.

The operation of the protective device from extraneous potentials is asfollows: Assume that the polarity of the applied potential is such thatconductors W1 and W2 are positive to ground. On one arrangement currentwill fiow from conductor W1 through condenser C1 through the elements ofgas tube N411 and its associated resistance to winding l of relay R1,thence through winding 2 of that relay and through the elements of gastube N431 and its associated shunt resistance to ground, resulting inoperation of relay R1, the contacts of which apply current to the shortcircuiting relays R10 and R20. results in a short circuit of all of theprotector blocks P1 to P4 and the gas tube arrangements connectedthereto, and current flowing from the various conductors W1 to W4traverses the Winding L1 of the transformer T and passes to ground.

Winding L2 of transformer T, by virtue of its connection to windings 3of relays R1 and R2 will, therefore, operate or hold operated both ofthese relays for the duration of the extraneous potential. The onlypotential existing across the gas tube arrangements and conductors W1 toW4 after operation of relays R111 and R20 will be that due to thevoltage drop in primary winding L1 of transformer T. This voltage willbe but'a few percent of that required to keep the glow present in thevarious gas discharge devices and hence these gas tubes will beextinguished.

For a potential between conductor W1 and ground of the opposite polaritythe operation will be as described with the exception that the currentwill pass from ground to the element of the gas tube N441 and itsassociated resistance, through windings l and 2 of the relay R1, thencethrough gas tube N421 to the condenser C1 and thence to conductor W1.The operation as described with respect to the gas tube arrangementinvolving condenser C1 applies equally well with respect to the gas tubearrangement associated with condenser C2.

Where it is desired to test the relay protector equipment by applyingpotential at some remote point, potential may be applied betweenconductors W1 and W2, the mid-point of the source of potential beinggrounded. Operation of relays R1 and R2 is brought about as follows:Assuming the potential applied to conductor W1 as positive and thatapplied to W2 as negative, current will flow from conductor W1 throughcondenser C1 through gas tube N411 and its associated shunt resistance,through the Winding I of relay R1, through winding 2 of relay R2 to gastube N422, condenser C2 and thence to conductor W2. Operation of therelays R1 and R2 is also brought about by reversing the potentialapplied between conductors W1 and W2 in which case current will passfrom conductor W2 through condenser C2, gas tube N412, winding l ofrelay R2, winding 2 of relay R1, through the gas tube N421 and itsassociated resistance, through condenser C1 and thence to conductor W1.This will ordinarily result in the operation of both relays R1 and R2.Thus, it will be noted that the voltage required to operate the gas tubearrangement by applying voltage between conductors W1 and W2 isequivalent to that required to operate the arrangement when thatpotential is applied between the conductor and ground. But the potentialto ground applied between these conductors is only onehalf of thepotential between wires.

Fig. 2 shows an arrangement similar to the one described with respect toFig. 1. The two relays R1 and R2 have been replaced by a single relayR3. This relay has a winding 3 which is connected to the secondarywinding of transformer The operation of said latter relays T and it alsoincludes two pairs of windings numbered ii and 2| and I 2 and 22 whichcorrespond to the windings l and 2 of relays R1 and R201 Fig. i. Theoperation, however, is identical to that as described with respect toFig. l.

In Fig. 3 operation of the relay protective device is brought about bythe breakdown in the aps of any one of the protector blocksor byvoltages applied between two selected conductors such as W1 and W3 or bythe voltage applied between any one of the conductors and ground.Biasing batteries A1 and A2, so poled as to increase or decrease thepotential required to cause a dim charge between the gaps of the tubesN41 or N42, are connected respectively to the anode of tube N41 and thecathode of tube N42, as shown. The mid-point or common terminus of thesebatteries is connected to the conductor W1. The operation of the gastube arrangement takes place as d scribed previously and therefore neednot be repeated. But one-quarter of the number of tubes are requiredhowever, and by means of the bias of batteries A1 and A2, the operatingvo tage or" these tube devices can be altered as desired.

Fig. 4 shows another a 'rangement for accomplishing the same resultusing but a single gas tube which operates the relay R5 when thepotential applied to conductor W2 is sufiiciently positive and thatapplied to conductor W1 is negative; or if conductor W1 is renderednegative and the ground is rendered positive. The arrangeis biased bybattery A which may be employed either to increase or to decrease theoperating voltage of the gas tube N4. A condenser may, if desired, beconnected across the lower winding of relay R5 for tuning its circuitfor op eration at a particular frequency.

Fig. 5 shows another arrangement for short circuiting conductors W1 andW2 upon the application of sufficiently high potentials to either orboth of these conductors. This arrangement includes a gas dischargedevice operating on the trigger principle and it is actuated bypotentials applied either between the conductors W1 and W2 or betweenconductor W1 and ground. The relay protector device will of course alsooperate from currents through the protector blocks due to potentialsapplied between the conductors and ground.

Conductor W1 is connected to condenser C1, the other side of saidcondenser being connected to the auxiliary electrode of gas tube N5. Thecathode K of the gas tube N5 is connected to the upper terminals ofcondenser C2 and winding 2 of relay R5. The other terminals of condenserC2 and winding 2 of relay Rs are connected to a source of potential B,the other side of which is connected to the armature of relay R7. Thecontact or relay R7 is connected to the anode A of gas tube N5. Thewindings of the short circuiting relay R10 and of relay R7 are bothconnected to th armature and contact of relay Rs through local batteryB.

The operation of the device is as follows: Voltage applied betweenconductors W1 and W2 or between conductor W1 and ground through condener (31 if of sunicient amplitude to cause glow to take place between theelectrodes of the gas tube N5 causes current to flow in the circuitwhich includes the anode A and the cathode K of the tube N5, winding 2of the relay R6, battery B, the armature and contact of relay R7 andthence back to the anode A of the gas tube N4. This current brings aboutoperation of the relay R6, causing its armature to be attracted to itscontact. The cloplied between conductors W1 and W2 or between conductorW1 and ground will hold relay Rs in the operated condition. The armatureof the relay R7 will be h ld away from its back contact during theperiod which the relay R6 is operated. Upon withdrawal of potential fromthe conductors and ground, relay R6 will restore to normal theconsequent restoration of the relays R19 and R7 to normal. The latterrelay R7 will reapply battery otential to the anode A of the gas tubeN4.

t will be understood of course that the relay Rs may be of themulti-contact type to provide short circuiting paths for protectors P1to P2, if so desired, in which case the relay R10 may be dispensed with.The arrangement is described only for a. pair of wires W1 and W2 but itis equally applicable to a multi city of conductors. Another and variedarrange ut for providing protector operation applica on of potentialbetween a pair of conductors disclosed in Fig. 5. Conductor W1 is conneoed to a condenser 01 in series with a pair of gas tubes N21 and N22which are shunted by resistances R1 and R2, respectively. These elementsare in turn connected in series with winding of the relay Re and withconductor W2. Conducto s W1 to W4. inclusive, are connected toprotectors P1 to P4, a transformer T and the winding i of relay Re. Theshort circuitin relays R10 and R20 are controlled by relay R6 andbattery 3 supplies the current necessary for their operation.

The operation of the arrangement for potentials applied to conductors W1and W2 is as follows: Potential of sufiicient amplitude to break downthe gaps or both gas tubes N21 and N22 but of insufiicient amplitude tooperate protectors P1 to P4, inclusive, passes current through winding'2 of relay Rs brings about its operation. Relay Rs operates r lays R10and R20, the armatures and contacts of which short circuit protectors P1to P4 in the normal manner.

The low impedance paths etween the conductors and ground through thearmatures contacts of relay R10 and R2u and the primary winding oftransformer T provides means for holding the relay R6 in the operatedcondition by virtue of the connection of its windin l to the primarywinding of transformer T. Relays Re and R10 and R20 will be heldoperated during the period in which suincient potential exists betweenany one or all of the conductors and ground, but these relays willrestore to normal immediately upon withdrawal of this potential. The gastube discharge devices 1 21 and N22 are, therefore, required to carrycurrent only for the period of time required to operate relay R6 andrelays R10 and R20. Resistances R1 and R2 are applied to tubes N21 andN22 for the purpose of insuring a definite breakdown potential for theseseries connected gas tubes. if but one tube is required, resistances R1and R2 may be omitted. It will also be understood that relay R may be ofthe multi-contact type, thus performing the functions of relays R andR20, etc., and, moreover,

that the number of conductors so protected need not be restricted tofour as indicated but may consist of a considerably greater number, ifso desired.

In each of these arrangements where the circuit is tested by applying avoltage between two conductors, such as W1 and W2, the testing voltageshould preferably be applied through a transformer, the secondary ofwhich is connected to these conductors and the midpoint of which isgrounded. If desired, the transformer may be replaced by a resistor orany other impedance or reactance the midpoint of which is grounded.

While this invention has been shown and described in certain particulararrangements merely for the purpose of illustration, it will beunderstood that the general principles of this invention may be appliedto other and widely varied organizations if departing from the spirit ofthe invention and the scope of the appending claims.

What is claimed is:

1. Apparatus for the protection of a plurality of signaling circuits,comprising a pair of gasfilled rectifier tubes connected in oppositionbetween two oi the signaling circuits so that alternate half cycles ofvoltage impressed between the said two signaling circuits will betransmitted through said tubes, and means responsive to the operation ofboth of said tubes for simultaneously grounding all of the signalingcircuits.

2. Apparatus for the protection of a plurality of conductors, comprisinga pair of gas-filled rectifier tubes, a pair of sources of potential,each of the tubes and each of the sources forming a series circuitbridging two of the conductors, and means responsive to the operation ofsaid tubes for simultaneously grounding all of the conductors.

3. Apparatus for the protection of a plurality of exposed conductorscomprising a pair of gasfilled rectifier tubes, a relay having twowindings each of which is connected in series with one of the tubesacross the same pair of exposed conductors, and means responsive to theoperation of said relay for simultaneously grounding all of the exposedconductors.

4. Apparatus for the protection of a plurality of exposed conductors,comprising a plurality of protector blocks one terminal of each of whichis connected to one of the exposed conductors, a saturating transformerthe primary winding of which is connected between the other terminal ofeach of the protector blocks and ground, a relay having three windingsone of which is connected to the secondary Winding of said transformer,a pair of gas-filled rectifier tubes connected in mutual oppositionacross the same pair of exposed conductors, each of said tubes beingconnected to one of the remaining windings of said relay, and meansresponsive to the operation of said relay for simultaneously groundingall of the exposed conductors.

5. Apparatus for the protection of a plurality of exposed conductorscomprising a gas-filled rectifier tube, a condenser, a relay having awinding connected in a circuit including said tube and said condenser,said circuit being connected across two of the exposed conductors, andmeans responsive to the operation of said relay for simultaneouslygrounding all of the exposed conductors,

6. Apparatus for the protection of a plurality of exposed conductorscomprising a condenser, a relay, two gas-filled tubes connected in acircuit including the winding of said relay and said condenser andextending to two of the exposed conductors, a pair of resistors each ofwhich is connected in shunt with one of said tubes, and means responsiveto the operation of said relay for simultaneously grounding all of saidconductors.

7. In an arrangement for the protection of a plurality of currentcarrying conductors, the combination of a plurality of protector blocks,a saturating reactor, each block being connected between one terminal ofthe reactor and one of the various conductors, the other terminal of thereactor being grounded, a relay having two windings one of which isconnected to said reactor, a pair of gas-filled tubes connected inseries with each other and with the other winding of said relay betweentwo of said conductors, a pair of resistors each of which shunts one ofsaid tubes, and means responsive to the operation of said relay forsimultaneously grounding all of said conductors.

LELAND KASSON SWART.

